Light control films (LCFs), including privacy filters such as 3M's Advanced Light control films (ALCF), is an optical film that is configured to regulate the directionality of transmitted light. Various
LCFs are known, and typically include a light transmissive film having a plurality of parallel louvers. Depending on the orientation of the louvers, the LCF may provide for maximum transmission at a predetermined angle of incidence with respect to the image plane and provide for image cut-off or black-out along a given polar coordinate (e.g., horizontally in the case of so-called privacy filters).
LCFs may be placed proximate a display surface. Typically, LCFs are designed such that at normal incidence, (i.e., 0 degree viewing angle, when a viewer is looking at an image through the LCF in a direction that is perpendicular to the film surface and image plane), the image is viewable. As the viewing angle increases, the amount of light transmitted through the LCF decreases until a viewing cutoff angle is reached where substantially all the light is blocked by the light-absorbing material and the image is no longer viewable. When used as a so-called privacy filter (for instance, for liquid crystal displays in computer monitors or laptop displays), this characteristic of LCFs can provide privacy to a viewer by blocking observation by others that are outside the view angle. 3M ALCF Privacy Filters are commercially available from 3M Company, St. Paul, Minn., under the trade designation “3M™ Filters for Notebook Computers and LCD Monitors.”
Matching the size of a privacy filter, or any other display film, to the display size is not a trivial task. It is important that the privacy filter or display film fit the display size properly to maximize the optical properties. Simply measuring the display size with a physical ruler can be difficult. Matching the correct model privacy filter or display film can be confusing to the consumer also.